I am smitten by this species, and it seems I am not the only one. Lampranthus is Latin for “shining flower”, while spectabilis means “outstanding”. “Outstanding shining flower” seems an apt common name for this species, but instead it is commonly termed trailing ice plant, after its translucent fleshy leaves.
Lampranthus spectabilis is a carpet-forming succulent shrub hailing from the Eastern Cape province of South Africa. It has 5cm wide flowers with a ring of narrow petals that come in pink, red, magenta, or purple; these circle a bright yellow centre. The wiry stems grow horizontally, and have small, finger-like fleshy leaves. This species grows to a height of about 30 cm, and is often covered in flowers. Not surprisingly, Lampranthus spectabilis is widely cultivated as an ornamental, particularly in hot arid climates where it is often featured in xeriscape gardens and also used to stabilize steep slopes and roadsides.
Trailing ice plant is also used on extensive green roofs, which have a very shallow soil profile to minimize weight on the underlying building. Succulents are common green roof plants, as they are able to store moisture in their fleshy leaves during wetter periods, allowing them to survive the extreme drought and heat found on extensive green roofs. Lampranthus spectabilis, like many succulents, has evolved another feature that allows it to survive in hot, dry environments. This species obtains carbon dioxide in a different way than most plants, through Crassulacean acid metabolism, or CAM. Species with CAM open their stomata (gas exchange pores) at night and on cloudy days, and so do most of their respiration when heat stress is at its lowest. CAM plants are able to close their stomata during the daytime, minimizing evaporation. However, they still have access to the CO2 stored from nightime respiration for the photosynthetic process. The saying “you can’t eat your cake and have it too” applies to ice plants as well as people–the CAM metabolism of Lampranthus spectabilis plants allow them to handle extreme drought and temperature, but also limit photosynthesis and results in plants being quite slow-growing. In a 2010 study by Sendo et al., Evaluation of Growth and Green Coverage of Ten Ornamental Species for Planting as Urban Rooftop Greening (PDF), the researchers found that trailing ice plant, although particularly hardy, was less effective on green roofs than many of the other evaluated species, due to its slow growth.